trigger AT_Opportunity on Opportunity (after update)
{

    AT_Opportunity_Trigger_Handler handler = new AT_Opportunity_Trigger_Handler(Trigger.isExecuting, Trigger.size);
     
    if(trigger.isUpdate)
    {
    	if(Trigger.IsAfter)
    	{
	        handler.OnAfterUpdate(Trigger.new, Trigger.newMap, Trigger.oldMap);
	    }
    }

}